Apparatus for drawing perspectives



July 10, 9 v R. J. ROBINSON 2,380,073

APPARATUS FOR DRAWING PERSPECTIVES Filed Nov; 24, 1945 5 Sheets-Sheet l5455 A/NE INVENTOR.

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APPARATUS FOR DRAWING PERSPECTIVES Filed Nov. 24, 1945 5 Sheets-Sheet 2IN VEN TOR. frzpfi/ Ff flea/Nam R. J. ROBINSON 2,380,073

APPARATUS FOR DRAWING PERSPECTIVES Filed Nov. 24, 1943 5 Sheets-Sheet 3l O $1 J .497 V I 71- 117' .10 86? I65 INVENTOR.

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APPARATUS FOR DRAWING PERSPECTIVES Filed Nov. 24, 1943 5 Sheets-Sheet 4VIII July R. J. ROBINSON 2,380,073

APPARATUS FER DEAWING PERSPECTIVES Filed Nov. 24, 1945 5 Sheets-Sheet 5lNi ENTOR. 24426 (I 10050160116 Arraemsx Patented JulylO, 1945 UNITEDSTATES PATE APPARATUS FOR DRAWING PERSPECTIVES Ralph J. Robinson, LosAngeles, Calif.

Application November 24, 1943, Serial No. 511,566

' 13 claims. ('01. 33-77) This application is a continuation-in-part ofmy copending application, Serial No. 459,610, filed September 25, 1942,and relates generally to the art of making perspective drawings.

More particularly, my invention relates to apparatus provided withmovable straight-edges which are pivoted about the vanishing points sothat for all positions of the machine, the straightedges pass throughthe vanishing points.

The major object of my invention is to provide a perspective machinewith which accurate perspectives can be rapidly produced without a greatdeal of previous training, and which therefore -makes possible theproduction of satisfactory drawings by persons relatively unskilled inthe m I Another object of my invention to provide perspective apparatuswhich is substantially foolproof in its operation, andwhich can bereadily adapted for various kinds of perspective work.

It is-also an object of my invention to provide apparatus of thecharacter described whichis verysturdy in construction and because ofits compact design can he used on drafting boards of various sizes tomake a wide "range of drawings.

vertical straight-edge mechanism which insures the proper position ofthe vertical straight-edge at all times, but which by suitableadjustment can be adapted to allow the straight-edge to assume otherangularpositions for particular purposes.

One of the principal features of my invention is the provision 'ofretractable straight-edges passing through the vanishing points at alltimes irrespective of theinposition. I r- These and other-objects andadvantages of my invention will become apparent from the follow... ingdescription ofa preferred form thereof, and from the accompanyingdrawings, in which: Fig. 1 is a perspective view of the apparatus of myinvention disposed on a drawing board, and being used for the productionof a perspective drawing, the full lines showing the machinein' oneposition, and the broken'lines showing it in another position. v

Fig. 2 is a top-plan view partially in section of the right-handvanishing point head which ineludes means forcontroliingthe verticalstraight- Fig. 3 is a front elevation partially in section of the headshown in Fig. 2,

18- 4 is a vertical section taken on the line 4-4 in Fig. 3,

Fig. 5 is a vertical-section taken on the line 5-5 in Fig. 3,

Fig. 6 is a vertical section taken on the line 6-6 in Fig. 3,

. Fi s. 7, 8, 9 and 10 are schematic views showing I the operation ofthe vertical straight-edge control means, I p Fig. 11 i a plan view ofthe movable center plate, the vertical straight-edge and the two van- 1ishing point straight-edges,

Fig. 12 is an enlarged vertical section of the center plate andadjusting knob mechanism taken on the line i2--l2 ofFig. 11,

Fig. 13 is an enlarged vertical section taken on the line l3-l 3 of Fig.12,

Fig. 14 is an enlarged vertical section taken on the line ll--ll of Fig.'11,

Fig. 15 is a bottom plan view of the center plate and verticalstraight-edge adjusting mechanism taken as indicated by the line l5-Iliin Fig. 12, and

F18. 16 is'a view similar to Fig. 15 illustrating the modification inmovement of the vertical.

- straight-edge when its control cables are adjusted to a differentposition.

. Referring now to the drawings, and particularly to Fig. 1 thereof, thenumeral 20 indicates generally the right-hand vanishing point head,which for brevity will hereinafter bereferred to as the right head, andwhich includes the contrbl. mechanism for the vertical straight-edge.

The numeral 2| indicates generally the left-hand vanishing point head,which will be referred to as the.left" head, while the numeral 22indicates generally the center plate assembly, all to ,b more fullydescribed in detail hereinafter. In Fig. I, the apparatus is shOWn asdisposed upon a drafting board 23, the right head 20 being securedthereto by thumb tacks 24 passing through suitable holes in a horizontalbase plate 25,

' 4,5 and the left head 2| being pivotally mounted to the drawing boardby means of a single thumb tack 26 fastening through a suitable hole ina base plate forming the bottom of the head It. Thecenter plate assembly22 includes a center plat 21 pivotally connected by means of pins 22 and28 respectively, to straight-edge supporting arms 30 and 3| which lieflat upon the drafting board and connect .to flexible tapes 32 and I3respectively. The tapes are preferably made of metal or other suitableflexible material which can be rolled on a reel.

carried by center plate 21.

first chosen for the particular to pivotally engage a vertical pin 35rigidly mounted in a rear housing 36 secured to the base plate 25. Therear housing 35 is thus held in fixed position on the board by means ofthe thumb tacks 2i and the forward housing 51 can be pivoted about thepin 25 during drafting operations.

Referring now to Figs. 2 to 4, inclusive, it is seen that the forwardhousing 31 has a horizontal shaft 38 mounted laterally therein whichcarries a pair of spring rollers 235 and ill connected thereto by spiralsprings 35 and. A l, respectively. The roller 39 rotates in a housing Aland carries a roll of flexible tape thereon, the free end 32 of whichpasses out through fixed housing 4| and around an idler roller 42 whichis rotatable on a horizontal shaft All mounted in As seen best in Figs.2, 3 and 5, the idler roller shaft 43 has a drum 45 secured thereto,this being accomplished by any suitable means such as the square shaftportion 21. The shaft 62 is provided with a knob 58 on one end thereofand is frictionally mounted in the housing 35 for rotation whensufficient torque is exerted on the knob 48, although normally the shaftremains stationary with the roller 52 rotating freely thereon. The drum56 carries a rubber or other resilient band 50 wound thereon whichextends under the roller 40 and through an aperture in the forward wallof housing 31 to connect with a suitable bracket on plate 21 for apurpose to be hereinafter discussed.

The left head 2| is preferably similar to right head 20 and includes aforward housing31 having a shaft 38 with a spring roller 39 thereoncarrying the flexible tape 33 which is adapted to be unwound and passedaround an idler roller 42. The head 2| also carries a drum '48 which hasa rubber or other resilient band 52 wound thereon and extendingoutwardly therefrom through the casing to an attachment bracket 52 Sincethese parts may be identical with corresponding parts in head 20, nodetails of the interior of head 2| have been illustrated, it beingthought sufficient to indicate its housing by the numeral 54, and theknob carried by the end of the idler roller shaft by the numeral 55.

The operation of these major parts of my apparatus in the production ofperspective lines passing through predetermined-vanishing points are asfollows. Desirable vanishing pointsare drawin to be made and the rightand left-hand heads are secured to the drafting board so that they willpivot about the chosen vanishing points. The retractable tapes 22 and 23with their respective straight-edge supporting arms ii and 3| secured tocenter plate 21 rest flat on the drawing board, and by, suitablemanipulation may be 'moved'to any position thereon, such for example asthe two positionsshown in Fig. 1. In all of these positions, the up redges of tapes 32 and 33 and their straight-edges 58 and 51 always passthrough'the vanishing points. In the illusaasaovs vanishing pointestablished by right head 20, and straight edge 51 has drawn all of thelines which pass through the vanishing point established by the lefthead 2|. While these portions of my apparatus are extremely useful inperspective drawing, I also provide means for drawing the necessaryvertical and near-vertical lines needed in perspective operations, andin addition I provide the proportional scales 50 and 52 previouslymentioned.

As previously mentioned, I form the proportional scale bands 50 and 52of rubber or other suitable elastic material which stretches uniformlyover its length. To these elastic bands.

I amx a plurality of markers 60 which are spaced along the bands fromthe center plate at progressively decreasing intervals to form aperspective measurement scale. The correct intervals of spacing for themarkers can be determined by known methods of perspective measurement orfrom charts, etc., available in the art. Since the bands stretchuniformly over their entire length, the ratios of the intervals betweenmarkers will remain the same for all positions of the center plate. Thetension on the bands can be adjusted by rotation of the knobs 18 anddrums 46 so that the initial spacing of the markers canbe set at anydesired amount.

and particularly to Figs. 1, 11 and 15 illustrating the assembly in planview, the .numeral 65 indicates a movable straight-edge, carried by thecenter plate 21 which, because it is normally held in a vertical ornear-vertical position, I will refer to herein as the verticalstraight-edge. This straight-edge 65 is pivotally mounted by a pin 66 toa normally vertical center bar 61 which in turn is rotatably mounted ona shaft 68 passing through the center plate 21. The center bar 51 ispivotally connected by a pair of parallel links 69 and 10 to a rockerarm -1| pivotally mounted on plate 21 by means of pin 28 which connectsthe plate 21 with straight-edge supporting arm 30. The rocker arm 1| andthe center bar 61 are arranged parallel to each other, and with parallellinks 69 and 10 form a parallelogram as seen best in Fig. 15. The centerplate 21 is provided with a knob 12 secured thereto by convenient meanssuch as screws 13, and the shaft 88 upon which the center bar 81 ismounted extends upwardly through a bore 14 in the knob 12 and isprovided with a head 15 fast to its upper end. The head 15 and shaft 61are urged upwardly by a. coil spring 16 which surrounds the shaft 61 andbears between the underside of the head 15 and the upward face of avertical bearing post 11 which rests on center plate 21 by virtue of anut 18 screwed on its mid-section. It will be noted that the post 11 isbored to permit the passage of shaft 68, and is provided with a head onits lower end 19 which is normally spaced just below the underface ofcenter plate 21 so that the post and shaft assembly float on the spring16. A friction washer U0 is inserted between head 19 and the, top of thecenter bar 61 to provide frictional contact therebetween, and a secondfriction washer II is inserted between the bottom of the center bar 21and a gear 22 which is fast to the lower end of shaft 88. Consequentlygear 82, center bar 81 and head 1| are normally held together as aunitby the combined action of the spring 1 and the C washers Ill and II, andare freely movable with tration shown in Fig. 1, the straight-edge 50has produced all of the lines which pass throueh the respect to centerplate 21 and itshandle knob 12. Returning now to Figs. 11 "and 15, itwillbc seen that a cable 95 is attached to the pivot pin 96 joining link19 and rocker arm 1|, and a similar cable 81 connects to pivotpin 88which joins link with rocker arm 11'. The cables 95 and 91 are led alongthe arm 39 through guides 89, 99, and 9! on the underside thereof,thence along the underside of tape 32 into the housing 91 and underneaththeidler roller 42.

The cables then pass through a guide aperture- 92 in a partition 94 inthe rear portion of the housing 91, and thence out through-an enlargedaperture 99 in the rear wall 95 of said housing. From aperture 99 thecable 85 passes around a pulley 99 mounted for rotation on a verticalshaft [Land thence to a guide aperture 98, then underneath the drum 6,and finally around the spring roller reel 49 to which it is attached.Similarly cable 86 passes from guide aperture 92 around a pulley 99rotatably mounted on a vertical shaft I99 and thence through the guideaperture 98, under drum 46, and around Jspring roller pulley 49 to whichit is also attached.

(See Fig.2.) 1

As seen best in Fig. 6, the vertical shafts 91 and I09 hung from ahorizontal screw shaft. lfll rotatably mounted inbearings I92 and H19 inthe side walls of housing 36, shafts 91 and N9 being threaded so thatrotation of the screw I91 causes the. vertical shafts to move inwardlyor outwardly together, the threads on the two ends of the screw shaftIlll being reversed so that the verticalshafts 91 and I!) will each moveinwardly or will each move outwardly as the case may be. The screw shaftI9! is providedwith a pinion gear 194 which is rotatably mounted inhousing 96 and provided with a knob I01 for manual adiuatment.

It will thus be seen that as the center plate is moved toward and awayfrom the right head 20 both the tape-92 and cables 85 and 81 will bewound and unwound on their respective spring rollers to maintain theproper tension thereon, it being understood that the cables shouldalways be the same length. The vertical shafts 91 and M9 are normallyspaced the same distance apart as the pivot pins 8t and 98 on rocker it,thus maintaining the parallelogram, and causing the rocker ill and itsassociated center bar 61 and vertical straight-eclge 65 to remainvertical at alltimes irrespective of the position of the center plate.This is best illustrated in Fig. 15 in which the solid lines show therelation of the parts for one position of the machine while the brokenlines indicate a different relative position for the arms and cableswith respect to the center- .plate when the plate has been .moved.However,

with variations in position of the center plate, it is only necessary torotate the knob I01 and shafts I09 and MI to vary the positions of thepulleys 96 and 99. Fig. 9 illustrates what happens to the rocker arm 1|and consequently to the center bar 91 and straight-edge 65 when thepulleys 99 and 99 are movedin toward each other. In this case, thevertical straight-edge is rotated in a clockwise direction asthe'center' plate moves along the base line. In Fig. 10, the opposite istrue where the pulleys 96 and 99 have been moved outwardly beyond theirnormal position, so that the rocker H and the vertical straight-edgerotate in a counter-clockwise direction. This is sometimes advisablewhen draw ing certain types of perspectives where it is desired to havethe lines that simulate the vertical lines inthe object being drawn,assume an angle, such for example, as in the case of a perspectivelooking up toward a long object such as a building. This situation isillustrated in Fig. 16 where the broken lines illustrate the position ofthe linkage and the respective parts when the pulleys 96 and 99 havebeen moved outwardly.

Under certain conditions it will be desirable to I have the verticalstraight-edge 65 normally assume an'angle away from the vertical and tomaintain that angleirrespective of the position of the center plate 21.For this purpose I have provided the rack and gear mechanism shown bestin Figs. 12, 14, 15 and 16 now to be described. As, previouslymentioned, the shaft 68 carries a gear 92' on its lower end which mesheswith a movable rack'i l0, slidable in a guide it provided by the head 61of the-center post 11.

it will be noted that the linkage comprising the recker it, links89 and19 and center bar 61 has not changed its position with respect to thecenmr plate 21. Consequently, once the cables are properly adjusted withthe vertical straight-edge in a vertical position, the straight edgewill maintain. this position at all times so long as the pulleys 98 and99 and their respective shafts 91 and .Idbare maintained at exactly thesame distance apart as'the pivot points 96 and 88. This relationship isfurther shown in Figs. '1 and 9- straightaedge-fl rotate one way'or theother The rack I I0 engages with a gear. H2 fast to the straight-edgeand rotatable therewith-about the pin 99 carried by. the center bar 61.Consequently, when the knob 15 is rotated manually, which can be done bypressing down on it to relieve the pressure exerted by spring 16, theshaft 98 and its gear 92 are rotated, which causes the rack lit] to movelongitudinally and rotate the gear M2, which in turn rotates thevertical straight-edge $5 to such riewposition as is desired. Once thestraight-edge 65 has been rotated to the desired position, the knob 15'is released and the spring it restores adequate friction contact betweenthe various parts so as to retain this straight-edge in this newrelative powill continue to occupy the same new angular position if theapparatus is set up for normal functioning so that the center bar staysvertical at all times.

It will be noted that the center plate 21 is provided with a lateralslot M5 to permit universal movement of center plate 2'! about the postit and its associated parts. This is helpful when it is desired tovernier the angular straight-edges Eh and bl into position. With theslot M5 the operator can, by grasping the knob it move the center platewith respect to the post and. shaft assembly in the slot lit to therebyvary the position of the straight edges 56 and 51 without dis-- turbingthe center bar and linkage.

As seen best in Figs. 11 and 14, the angular straight-edges 56 and 5,1are supported on the arms 39 and 3| by means of thumb screwclamps H5 andH1 so that they can be removed or adjusted as desired, although normallythey are aligned with their respectivetapes.

From the foregoing description of a preferred form of my device, it willbe seen that Ihave provided a perspective drawing instrument which makespossible practically complete mechanical production of perspectives, sothat one relatively unskilled in the art, can, after a few simplelessons with my machine, draw the most dlfllcuit perspectives in a veryshort time. The truth or this fact has been borne out by extended use ofthe machines by novices in the art of drafting, and exceptionally fineresults have been obtained. It is to be understood of course that whileI have illustrated and described one form of my invention withconsiderable particularity, I do not mean to limit myself to the variousdetails shown, but rather intend that my invention should be given thefull scope of the appended claims.

I claim:

. 1. In apparatus for the production oi perspective drawings-by the useof vanishing points, the combination-o1: a pair of heads adapted to bemounted on a drawing board to establish said vanishing points;retractable means housed in each of said heads; and a center platepivotally connected to the free ends of said retractable means, wherebymovement of said plate over said board will cause movement of each ofsaid retractable means.

2. In apparatus for the production of perspective drawings by the use ofvanishing points, the combination of: a pair of heads adapted to bemounted on a drawing board to establish said vanishing points; aflexible tape housed in each of said heads; and means pivotailyconnecting the free ends of said tapes, whereby movement or vanishingpoints;

said connecting means over said board will cause movement of each ofsaid tapes.

3. In apparatus for the production of perspective drawings by the use ofvanishing points, the combination of: a pair ofheads adapted to bemounted on a drawing board to establish said vanishing points; aflexible tape mounted on a spring roller housed in each of said heads;and

, a center plate pivotaily connected to the tree nected to saidstraight-edge by a ends of said tapes, whereby movement of said plateover said board will cause movement or said tapes.

4 In apparatus for the production oiperspective drawings by the use ofvanishing points, the combination of: a pair of heads adapted to bemounted on a drawing board. to establish said vanishing points;retractable means housed in each of said heads; and a center platecarrying a normally vertical straight edge pivotally connected to thefree ends of said retractable means, whereby movement of said plate oversaid board will cause movement of each oi said retractable means. 5. Inapparatus for the production of perspective drawings by the use ofvanishing points, the combination of: a pair of heads adapted to bemounted on a drawing board to establish said vanishing points; aflexible tape mounted ona spring roller in each of said heads; and meanspivotaily connecting the free ends of'said tapes, whereby movement ofone of said tapes oversaid board will cause complemental movement of theother of said tapes. 4

6. In apparatus for the production of perspective drawings by the use ofvanishing points, the combination of: a pair of. heads adapted to bemounted on a drawingboard to establish said 'vanishing points; aflexible tape mounted on a carrying a normally vertical straight edgepiv otally connected to the free ends or said tapes: and meansoperatively associated with one of said heads and said plate formaintaining said straight edge in a predetermined position at all times,irrespective of its position on said board.

'7. In apparatus for the production 0! perspective drawings by the useof vanishing points, the combination of a pair of heads adapted to bemounted on a drawing board to establish said a spring roller rotatablymounted in each of said heads; a flexible tape wound on each of saidrollers with its free end extending out of said housing; a center platepivotaily connecting the free ends of said tapes to eflect universal andsimultaneous movement thereof over said board; astraight edge carried bysaid center plate and adapted to normally be in a substantially verticalposition; means operatively associated with one of said heads forcontrolling the position of said straight edge, comprising a springroller, cable spacing means, and a pair of cables connected to a rockeron said center plate; and a pair of parallel links connecting saidrocker to said straight edge whereby the latter will assume apredetermined position for every position of said center plate on saidboard.

8. In apparatus for the production 0! perspective drawings by the use ofvanishing points, the combination of: a pair oi heads adapted to bemounted on a drawing board to establish said vanishing points; a springroller rotatably mounted in each oi'said heads; a flexible tape wound oneach of said rollers with its free end extending out of said housing: acenter plate pivotally connecting the free ends of said'tapes to effectuniversal and simultaneous movement thereof over said board;astraight-edge carried by said center plate and adapted to normally bein a substantially vertical position; a rocker pivotally mounted on saidcenter plate and conpair 01' parallel links; a pair of cables extendingfrom said rocker to spring roller means within one of said heads; andguide means for guiding said cables vwound on each 01' said rollers withits free end extending out of said housing; a center plate pivotallyconnecting the free ends of said tapes to eilect universal andsimultaneous movement thereof over said board a straight-edge carried bysaid center plate and adapted to normally be in a substantially verticalposition; a rocker pivotally mounted'on said center plate and connectedto said straight-edge by a pair of parallel links; a pair of cablesextending i'rom said rocker to spring roller means within one of saidheads; and a pair of guide rollers for said cables associated with saidhead and adjustable toward and away from each other to vary the spacingof said cables, whereby said straightedge may be caused to rotate uponmovement 01' said center plate.

10. In apparatus for the production 01' perspective drawings by the useof vanishing points, the combination of: a pair oi heads adapted to bemounted on a drawing board to establish said vanishing points; a springroller rotatably mounted in each oi. said heads; a flexible tape woundon each of said rollers with its free end extending out of said housing;a center plate a,aeo,o7a

able tape mounted within pivotally connecting the free ends of saidtapes to effect universal and simultaneous movement thereof over saidboard;

engaging said gear; a normally vertical straight-edge pivotally mountedto, said center bar and 11. In apparatus "for the spective drawings bythe use the combination of: otally mounted on a production of perofvanishing points, a head adapted to be pivsaid head and adapted to beextended therefrom; a spring roller in said h'ead upon which said tapeis wound; a plate wound on said roller out of said housing; a centerplate pivotally connected to the-free end of saidtape; a straightedgecarried by said center plate and. adapted to normally be in asubstantially vertical position; means operatively' associated with saidhead for controlling the position of said straightedge, comprising aspring roller, cable spacing means, and a-pair of cables connected to arocker on said center plate; and a pair of par- ,allel links connectingsaid rocker to said straight edge whereby the latter will assume apredetermined position for every position of said center plate on saidboard.

RALPH J1! ROBINSON.

the production of per-

